Why would the front differential dipstick get pushed out and spray oil on a 99 Subaru legacy outback It has been -30 and my car hasn't ran for a couple days When it did start it did this?

The reason for a oil spray out of the front differential dipstick in a 1999 Subaru Legacy is because of the cold. While it was -30 the car oil thickened, when the engine started and tried to pull the oil through, pressure was created.The engine was not able to pull the thickened oil in and the pressure pushed the oil out of the dipstick.